Thin Film Solar Power - Cheaper than Coal ?  

Thin film solar company Nanosolar has now shipped its first solar panels and begun an auction for the second panel produced - now cancelled by eBay because Nanosolar decided to donate the purchase price to charity (the third pnael has been donated to the Tech Museum in San Jose, california), leading to speculation that the (direct) cost of solar power is now cheaper than coal (and falling).

While it is still too early to tell whether or not Nanoslar can meet their goal of producing cells at $1 per watt, the fact that the company has constructed a manufacturing plant and begun shipping the product to a paying customer (in Germany) is a good sign.

The first plant is reportedly capable of producing 430 megawatts a year of cells, which is a respectable amount compared to the total amount of photovoltaic manufacturing capacity currently in place.

Nanosolar's cells are made of Copper Indium Gallium Selenide (CIGS). They aren't the only company working in this area - competitors include Heliovolt and the struggling Miasole. Other thin film solar manufacturers are working with materials like Amorphous Silicon (a-Si) - for example Power Film, XSunX and United Solar Ovonic - or Cadmium Telluride (CdTe) - for example First Solar. Konarka also sell "power plastic" (soon to be marketed in Australia by Skyshades) using "Graetzel cells" based on a thin coating of ruthenium and organic bipyridine molecules over a titanium substrate.

One potential issue to watch as manufacturing volumes are scaled up is the availability of the various materials that make up thin film cells.

Availability and price of Tellurium are already concern to analysts of First Solar, though there is speculation that copious amounts of Tellurium can be mined from deep sea ridges.

There appear to be similar concerns about availability of indium in particular (and to a lesser extent gallium) for CIGS cells, though as usual concrete data on total reserves for these seems to be in short supply as well.

Nanosolar's technology is reportedly capable of achieving higher efficiency rates (up to 19.5%) than are achieved with other thin-film technologies. However, these efficiency rates have only been seen under laboratory conditions so far. Mass produced CIGS solar cells usually have efficiency rates of 12%-15% – making them about half as efficient as their silicon PV counterparts.